Display device and transport means

Abstract

The present invention relates to a display device (1) and to a transport means comprising such a display device (1). The display device (1) has a display panel (2) and a backlight (3) for the display panel (2). The backlight (3) comprises a reflector (30) having a large number of reflective cavities (31) and a large number of light sources (32) arranged in each of the cavities (31). The cavities (31) are designed to allow cross-luminance of the light (L), emitted by the light sources (32), into adjacent cavities (31). In the process, cross-luminance into the cavities (31) arranged in an edge region (300) of the reflector (30) is reduced.

Description

[0001] Description

[0002] Display device and means of transport

[0003] The present invention relates to a display device and a means of transport with such a display device.

[0004] The number and area of ​​display devices in vehicles are constantly increasing. Display devices can be found on the market, for example, as instrument clusters for the driver, as central displays, and even as passenger displays. Non-self-luminous transmissive displays require backlighting to display the image. The purpose of the backlight is to illuminate the display panel as evenly as possible across the entire active area, creating the most homogeneous display possible right up to the edges.

[0005] Matrix backlights use a multitude of light sources arranged in a matrix to generate light. A reflector directs the light from the light sources toward the display panel.

[0006] For example, DE 10 2007 007 353 A1 describes a lighting device with a luminous surface that can be modularly assembled from a plurality of radiation reflectors. Honeycomb-shaped, scale-shaped, triangular, or rectangular radiation reflectors are preferably used. Each of the radiation reflectors has a plurality of radiation-reflecting surfaces that are curved outwardly from a center in which a light source is arranged.

[0007] The backlighting provided by the matrix backlight often depends on the displayed content. For example, only those light sources are activated above which content is displayed on the display panel. The cavities of the reflector, in which the light sources are arranged, are designed so that the light from one cavity spills over or overilluminates neighboring cavities to avoid strong brightness gradients.

[0008] For example, US 2020 / 0287109 A1 describes an electronic device comprising a substrate, light-emitting elements, and a confinement structure. The light-emitting elements are arranged on the substrate. The confinement structure is arranged adjacent to the light-emitting elements.

[0009] CN 103742840 A describes a backlight comprising a hollow body in which light-emitting diodes are arranged, and an optical plate arranged on the hollow body. The side walls of the hollow body are reflective and have different heights.

[0010] The active area of ​​display devices is often defined by a light-tight, usually black border. This can be implemented, for example, as a printed disc arranged in front of the display panel. When content is displayed on a black background at a distance from this border, the black background is also illuminated in the distance area. This results in a clearly visible demarcation or light-dark contrast between the actual black background and the black border. The viewer perceives two surfaces: the illuminated black background in the display panel and the black border.

[0011] It is an object of the invention to provide an improved display device with a matrix backlight.

[0012] This object is achieved by a display device having the features of claim 1 and by a means of transport according to claim 10. Preferred embodiments of the invention are the subject of the dependent claims.

[0013] According to a first aspect of the invention, a display device comprises a display panel and a backlight for the display panel, the backlight comprising:

[0014] - a reflector with a plurality of reflective cavities; and

[0015] - a plurality of light sources each arranged in the cavities, wherein the cavities are designed to allow crosstalk of the light emitted by the light sources into adjacent cavities, and wherein the crosstalk into the cavities arranged in an edge region of the reflector is reduced.

[0016] The inventive solution structurally reduces overexposure or crosstalk into the adjacent cavities in the edge area. Due to the reduced crosstalk, the brightness difference between the black edge and the actual black background is smaller. This makes the display device appear more high-quality, and the contrast appears higher. Furthermore, it becomes more difficult for the viewer to distinguish between the display surface and the black edge.

[0017] According to one aspect of the invention, the cavities arranged in the edge region of the reflector have a different design than the other cavities of the reflector to reduce crosstalk. By designing the cavities differently, the structural reduction of crosstalk can be achieved cost-effectively. In particular, no additional components are required.

[0018] According to one aspect of the invention, walls of the cavities in the edge region of the reflector have an at least partially reduced distance from a component arranged above the reflector or an at least partially increased wall thickness. Alternatively, the cavities in the edge region of the reflector have a reduced footprint or an increased depth. All of the aforementioned approaches result in a reduction in the amount of light emitted by the light sources that is not blocked by the walls of the cavities and can thus enter neighboring cavities. The aforementioned approaches for reducing crosstalk can also be implemented in combination.

[0019] According to one aspect of the invention, the walls of the cavities are rounded, and the cavities are designed to reflect the light emitted by the light sources toward the display panel. This rounding allows the emitted light to be reflected more precisely toward the display panel. Alternatively, the walls can also be straight, similar to a pyramid.

[0020] According to one aspect of the invention, the light sources are side-emitting light-emitting diodes or surface-emitting light-emitting diodes. The light sources are preferably side-emitting light-emitting diodes, in particular light-emitting diodes that emit light from all sides. The use of side-emitting light-emitting diodes has the advantage of preventing the formation of light spots in the backlight. This ensures a particularly homogeneous illumination of the display panel. However, the solution according to the invention can also be used in conjunction with surface-emitting light-emitting diodes.

[0021] According to one aspect of the invention, the edge region of the reflector comprises two or more rows of cavities. This allows the area of ​​the display device in which a brightness difference to the edge of the display device is reduced to be enlarged. According to one aspect of the invention, the reduction of crosstalk occurs gradually across the two or more rows of cavities. In this way, the reduction of crosstalk toward the edge of the display device can occur in an approximately continuous transition.

[0022] According to one aspect of the invention, the crosstalk reduction in the edge region of the reflector is achieved either uniformly or non-uniformly. Whether the crosstalk reduction should be more uniform or non-uniform can be determined depending on the size of the display device or the other design of the display device or the installation situation of the display device.

[0023] According to one aspect of the invention, the cavities form a grid of polygons. For example, the cavities can form a rectangular grid or a hexagonal grid. The reflector can be designed in various ways. The arrangement of the cavities in a grid of polygons allows the reflector to be formed from a continuous matrix of cavities.

[0024] According to one aspect of the invention, an active area of ​​the display device is at least partially delimited by a light-tight enclosure. Many display devices have such a light-tight enclosure to achieve a particularly high-quality appearance. However, with regard to the problem mentioned, a light-tight enclosure is associated with a particularly pronounced difference in brightness. The use of the solution according to the invention is therefore particularly advantageous for a display device designed in this way.

[0025] A display device according to the invention is preferably used in a means of transportation. The means of transportation can be, for example, a motor vehicle, but alternatively also an aircraft, a rail vehicle, or a watercraft. Further features of the present invention will become apparent from the following description and the appended claims in conjunction with the figures.

[0026] Figure overview

[0027] Fig. 1 shows schematically a cross section of a display device according to the prior art;

[0028] Fig. 2 illustrates the crosstalk of light between cavities of the display device of Fig. 1;

[0029] Fig. 3 shows schematically a cross section of a first embodiment of a display device according to the invention;

[0030] Fig. 4 illustrates the crosstalk of light between cavities of the display device of Fig. 3;

[0031] Fig. 5 shows schematically a cross section of a second embodiment of a display device according to the invention;

[0032] Fig. 6 shows schematically a cross section of a third embodiment of a display device according to the invention;

[0033] Fig. 7 shows schematically a cross section of a fourth embodiment of a display device according to the invention;

[0034] Fig. 8 shows schematically a cross section of a fifth embodiment of a display device according to the invention; Fig. 9 shows schematically a cross section of a sixth

[0035] Embodiment of a display device according to the invention; and

[0036] Fig. 10 shows schematically a means of transport that uses a display device according to the invention.

[0037] Character description

[0038] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. Like reference numerals are used in the figures for like or equivalent elements and are not necessarily described again for each figure. It is understood that the invention is not limited to the illustrated embodiments and that the described features can also be combined or modified without departing from the scope of the invention as defined in the appended claims.

[0039] Fig. 1 shows a schematic cross-section of a display device 1 according to the prior art. The display device 1 has a display panel 2 that is glued to a cover glass 4. The display panel 2 has an active region 8 that is delimited by a light-tight enclosure 9. The boundary of the active region 8 is indicated in Fig. 1 by a dashed line. The light-tight enclosure 9 can be realized, for example, by printing on the cover glass 4 or by a separate mask. The cover glass 4 closes off a housing 7 of the display device 1 from the environment. A backlight 3 for the display panel 2 is arranged in the housing 7. The backlight 3 has a reflector 30 with a plurality of cavities 31. A light source 32, typically a light-emitting diode, is arranged in each of the cavities 31.The light sources 32 are arranged on a circuit board 34, which can be glued to the housing 7. The reflective walls 33 of the cavities 31 of the reflector 30 are rounded and orient the light L emerging from the light sources 32 towards the display panel 2. Alternatively, the walls 33 can also be straight, similar to a pyramid. In the example shown, an optical plate 5 with an optical film stack 6 arranged thereon is located between the backlight 3 and the display panel 2. The films of the optical film stack 6 have the task of scattering, collecting, or directing the light L from the reflector 30 in such a way that the requirements for the solid angle of the backlight 3 are met. Typical films for light alignment are brightness enhancement films (BEF) and light control films (LCF).The optical plate 5 is a transparent plate that ensures the optical distance between the optical film stack 6 and the light sources 32. The cover glass 4, the optical plate 5, and the housing 7 are connected to one another by suitable connecting elements, e.g., adhesives. The walls 33 of the cavities 31 do not extend as far as the optical plate 5, i.e., they are continuously spaced at a distance Di from the optical plate 5. This ensures crosstalk of the emitted light L into neighboring cavities 31, which is indicated in Fig. 1 by the light cones drawn.

[0040] Fig. 2 illustrates the crosstalk of light between the cavities 31 of the display device 1 from Fig. 1 . The active region 8 can be seen, which is delimited by the light-tight border 9. The cavities 31 can also be seen. Two active cavities 31 are shown as examples, identified by the letter “a”. Due to the design of the cavities 31, crosstalk of the emitted light occurs into the neighboring cavities 31, identified by the letter “b”. This crosstalk of light is not a problem inside the active region 8, since it does not lead to a large difference between light and dark with respect to the light-tight border 9. This is the case in Fig. 2 for the active cavity 31 in the left half of the active region 8.In the active cavity 31 shown in the right half of the active area 8, however, light crosstalk occurs in cavities that are directly adjacent to the light-tight enclosure 9 or partially covered by it. This leads to a large light-dark difference, which is perceived as disturbing by the observer.

[0041] Fig. 3 schematically shows a detailed view of a first embodiment of a display device 1 according to the invention. The display device 1 largely corresponds to the display device 1 shown in Fig. 1, but the crosstalk in an edge region 300 of the reflector 30 is structurally reduced. In the illustrated embodiment, this is achieved in that the walls 33 of the cavities 31 in the edge region 300 of the reflector 30 have an at least partially reduced distance from the display panel 2 or the optical plate 5. Thus, two different wall heights or distances Di and Ö2 are used, with Ü2 <DI . Dies führt dazu, dass die Menge des von den Lichtquellen 32 abgestrahlten Lichts L, das nicht von den Wänden 33 der abweichend ausgestalteten Kavitäten 31 geblockt wird und somit in diese Kavitäten 31 eintreten kann, verringert wird. Dies ist durch die eingezeichneten Lichtkegel angedeutet.In the illustrated embodiment, only the outermost cavities 31 have raised walls 33, ie the edge region 300 comprises only a single row of cavities 31. In an exemplary configuration, the total structural height of the display device 1 is preferably in the range of -13.3 mm. The height of the reflector 30 can be ~3.72 mm, the width of the walls 33 at their widest point ~6.13 mm. The distance between the film stack 6 and the display panel 2 is, for example, ~1.31 mm, the distance between the reflector 30 and the optical plate 5 can be -1.05 mm. The distance between the light sources 32 can be, for example, -9.13 mm.

[0042] Fig. 4 illustrates the crosstalk of light between the cavities 31 of the

[0043] Display device 1 from Fig. 3. The active area 8, which is delimited by the light-tight border 9, can again be seen. The cavities 31 are also visible. Two active cavities 31 are shown as examples, identified by the letter "a". Due to the design of the cavities 31, crosstalk of the emitted light occurs into the neighboring cavities 31, identified by the letter "b". Due to the reduced crosstalk between the cavities 31 in the edge region of the reflector, however, the light-dark difference is now reduced for those cavities 31 that are directly adjacent to the light-tight border 9 or are partially covered by it. This is clearly visible in the active cavity 31 shown in the right half of the active area 8. This, in turn, means that the remaining light-dark difference is perceived as less disturbing by the observer.

[0044] Fig. 5 schematically shows a cross section of a second embodiment of a display device 1 according to the invention. The display device 1 largely corresponds to the display device 1 shown in Fig. 3, but in this case the edge region 300 comprises two rows of cavities 31. In the example shown, the reduction of the crosstalk takes place gradually over the two rows of cavities, ie, three different wall heights or distances Di, Ö2 and Ü3 are used, with D3 <D2<DI .

[0045] Fig. 6 schematically shows a cross-section of a third embodiment of a display device 1 according to the invention. The display device 1 largely corresponds to the display device 1 shown in Fig. 3, but the display panel 2 and the cover glass 4 are curved in this case. The curvature can in particular be convex or concave, but any desired free form is also possible. The wall heights are selected such that the distance Di to the display panel 2 or to the optical plate 5 is constant. Only in the case of the cavities 31 in the edge region 300 of the reflector 30 do the walls 33 have an at least partially reduced distance Di to the display panel 2 or to the optical plate 5. Thus, two different distances Di and D2 are used, with D2 <DI . Die daraus resultierende Reduzierung des Übersprechens ist wie zuvor durch die eingezeichneten Lichtkegel angedeutet.

[0046] Fig. 7 shows a schematic cross-section of a fourth embodiment of a display device 1 according to the invention. The display device 1 largely corresponds to the display device 1 shown in Fig. 3, but in this embodiment no different wall heights or distances are used. Instead, the crosstalk in the edge region 300 of the reflector 30 is structurally reduced in that the walls 33 of the cavities 31 in the edge region 300 have an at least partially increased wall thickness Wi. The wall thickness Wi here refers to the thickness of the wall 33 at the upper end facing the optical plate 5. Thus, two different wall thicknesses Wi and W2 are used, with W2>Wi. In this way, it is also achieved that the amount of light L emitted by the light sources 32, which is not blocked by the walls 33 of the differently designed cavities 31 and can therefore enter these cavities 31, is reduced.This is indicated by the light cones shown.

[0047] Fig. 8 shows a schematic cross section of a fifth embodiment of a display device 1 according to the invention. The display device 1 largely corresponds to the display device 1 shown in Fig. 5, but in this embodiment no different wall heights or distances are used. Instead, the crosstalk in the edge region 300 of the reflector 30 is structurally reduced in that the cavities 31 in the edge region 300 have a smaller width and thus also a smaller base area. In the example shown, the edge region 300 again comprises two rows of cavities 31. Due to the smaller width, the opening angle of the light cone in the differently designed cavities 31 is also reduced, so that less light L can crosstalk into the neighboring cavities 31. The smaller width of the cavities 31 in the edge region 300 leads to a higher density of the light sources 32 in this region.The resulting higher luminous intensity must be compensated by using light sources 32 with lower light output or by an adapted control of the light sources 32.

[0048] Fig. 9 shows a schematic cross section of a sixth embodiment of a display device 1 according to the invention. The display device 1 largely corresponds to the display device 1 shown in Fig. 5, but in this embodiment no different wall heights or distances Di are used. Instead, the crosstalk in the edge region 300 of the reflector 30 is structurally reduced in that the cavities 31 in the edge region 300 have a greater depth. In the example shown, the edge region 300 again comprises two rows of cavities 31. The greater depth also reduces the opening angle of the light cone in the differently designed cavities 31, so that less light L can crosstalk into the neighboring cavities 31. To realize cavities 31 of different depths, it is expedient to arrange the respective light sources 32 on separate printed circuit boards 34.

[0049] Fig. 10 schematically shows a means of transport 100 that uses a display device 1 according to the invention. In this example, the means of transport 100 is a motor vehicle. The motor vehicle has a display device 1 according to the invention, which is arranged in a dashboard. Data on the vehicle's surroundings can be acquired using a sensor system 101. The sensor system 101 can in particular comprise sensors for environmental detection, e.g., ultrasonic sensors, laser scanners, radar sensors, lidar sensors, or cameras. The information acquired by the sensor system 101 can be used to generate content to be displayed for the display device 1. Further components of the motor vehicle in this example are a navigation system 102, by means of which position information can be provided, and a data transmission unit 103. By means of the data transmission unit 103, for example,A connection to a backend can be established, for example, to obtain updated software for components of the motor vehicle. A memory 104 is provided for storing data. Data exchange between the various components of the motor vehicle takes place via a network 105.

[0050] List of reference symbols

[0051] 1 display device

[0052] 2 display panel

[0053] 3 Backlight

[0054] 30 reflector

[0055] 300 edge area

[0056] 31 Cavity

[0057] 32 light source

[0058] 33 Wall

[0059] 34 circuit board

[0060] 4 Cover glass

[0061] 5 Optical disk

[0062] 6 stacks of slides

[0063] 7 housings

[0064] 8 Active area

[0065] 9 Light-tight frame

[0066] 100 means of transport

[0067] 101 Sensor Technology

[0068] 102 Navigation system

[0069] 103 Data transmission unit

[0070] 104 memory

[0071] 105 Network

[0072] The distance

[0073] L Light

[0074] Ti depth

[0075] Wi wall thickness

Claims

Patent claims 1. Display device (1) with a display panel (2) and a backlight (3) for the display panel (2), wherein the backlight (3) comprises: - a reflector (30) having a plurality of reflective cavities (31); and - a plurality of light sources (32) each arranged in the cavities (31), wherein the cavities (31) are designed to allow crosstalk of the light (L) emitted by the light sources (32) into adjacent cavities (31), and wherein the crosstalk into the cavities (31) arranged in an edge region (300) of the reflector (30) is reduced.

2. Display device (1) according to claim 1, wherein the cavities (31) arranged in the edge region (300) of the reflector (30) have a design that differs from the other cavities (31) of the reflector (30) in order to reduce crosstalk.

3. Display device (1) according to claim 2, wherein walls (33) of the cavities (31) in the edge region (300) of the reflector (30) have an at least partially reduced distance (Di) to a component (2, 5) arranged above the reflector (30) or an at least partially increased wall thickness (Wi), or wherein the cavities (31) in the edge region (300) of the reflector (30) have a reduced base area or an increased depth (Ti).

4. Display device (1) according to claim 3, wherein the walls (33) of the cavities (31) are rounded or straight-lined similar to a pyramid and the cavities (31) are designed to reflect the light (L) emitted by the light sources (32) in the direction of the display panel (2).

5. Display device (1) according to one of the preceding claims, wherein the edge region (300) of the reflector (30) comprises two or more rows of cavities (31).

6. Display device (1 ) according to claim 5, wherein the reduction of the crosstalk occurs gradually across the two or more rows of cavities (31 ).

7. Display device (1) according to one of the preceding claims, wherein the reduction of the crosstalk in the edge region (300) of the reflector (30) takes place uniformly or non-uniformly.

8. Display device (1) according to one of the preceding claims, wherein the cavities (31) form a grid of polygons.

9. Display device (1) according to one of the preceding claims, wherein an active region (8) of the display device (1) is at least partially delimited by a light-tight enclosure (9).

10. Means of transport (100) with a display device (1) according to one of the preceding claims.

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